The popularity of backpacks has increased in recent years. They are widely used for day hiking, bicycling, and climbing as well as for carrying books and supplies by students.
As the national emphasis continues to be placed on improving the design of a book container or carrying bags, there is a need for a container which can be opened and closed more efficiently and which can hold the objects more firmly.
Moreover, there is a need for a book container that can provide immediate visual feedback of inner contents without the need to open up the container itself.